Spark plugs



Jan. 12, 1960 E. J. NOVAK SPARK PLUGS Filed' Dec. 2 1955 J. /Vowm WM ATT RNEY5 l `tegral-,with the body thereof.

vUnited States. Patent i This invention relates `generally to spark plugs, and

`is particularly directed 'to gaskets permitting the use of conventional spark"l plugs in engines designed for use with corresponding special spark plugs.

Automobiles now being manufactured by the same manufacturers, have their engine heads machined with `bevel seats to receive special spark plugs formed with corresponding bevel seats integral with the body of the plug. The initial installation of such special spark plugs at the factory causes no difficulty. However, when the spark plugs are to be replaced, the replacement of the original special -spark plugs frequently results in damage to the seats byreason of the hard metal-to-hard metal contact therebetween, andleaks then occur between the damaged seatsto cause loss of power and generally poor operation. When the seats of the engine head have been damaged, the necessary tight fit between the head and spark plug seats can be restored only by resurfacing of the engine head seats, and this is an expensive and troublelsoin'e operation, requiring the use of special tools designed for' that purpose.

Accordingly, it is anobject of this invention to provide Ygaskets "for use in connection with engine heads having bevel seats for the spark plugs to prevent damage to such seats upon' replacement of the original special spark plugs.

Another object is to provide bevel gaskets for use in connection with engine heads having bevel seats for the -spark vplugs to' permit the replacement of the original 'special plugs havingsimilar bevel seats integral with the bodies by conventionalA plugs having seats extending radially or at right angles to the axes of the plugs.

Iniaccordance with the present invention, a ring-like v Lgasket of relatively soft metal having good heat conduct- "ing characteristics, for example, copper or the like, is

formed with a bevelled outer surface to tit between the radially extending seat of a conventional spark plug and the bevel seat of au engine cylinder head intended to accommodate ya'fspecial spark plug having a bevel seat in- Such'ai bevel gasket avoids damage to the bevel seat l,of the cylinder head during the installation of a new sparkplug'by'reas'on of the relative softness of the material fr'rmwhich itis formedand permits the replacement of the special plugs intended for use in engines having bevel seats by conventional plugs. Further, when the spark plug is tightened, the bevel gasket is compressed and deformed to the extent necessary to provide an effective seal and good heat conductivity between the seats of the head and spark plug, thereby ensuring good engine performance andincreasing'the useful life of the spark plug.

The above, and other objects, features and advantages of the invention, will be apparent in the following detailed description of illustrative embodiments which is to be read in connection with the accompanying drawing forming a part hereof, and wherein:

Fig. l is an elevational view, partly in section, showing a conventional spark plug installed in a cylinder head having a bevel seat with a gasket disposed between the seats of the spark plug and cylinder head in accordance with a first embodiment of this invention;

Fig. 2 is a top plan view of the gasket of Fig. 1;

Fig. 3 is an elevational view, partly broken away and in section, of the gasket of Figs. 1 and 2;

Fig. 4 is a fragmentary elevational view, partly is section, showing-a conventional spark plug installed in a cylinder head having a bevel seat with a gasket disposed between the seats of the spark plug and cylinder head in accordance with another embodiment of this invention;

Fig. 5 is a top plan view of the gasket of Fig. 4;

Fig. 6 is an elevational view, partly broken away and in section, of the gasket of Figs. 4 and 5.

Referring to the drawings in detail, and initially to Fig. 1 thereof, a portion of a cylinder head is there shown in section and generally identified by the 'reference numeral 10. The head 10 has an internally threaded bore 11 extending therethrough to receive the threaded body of a spark plug, and the upper or outer end of the bore 11 is counter-sunk to define a bevel seat 12, such as, for example, in automobiles produced by the Ford Motor Company under the designations Ford, Mercury and Lincoln. Engine heads having bevel spark plug seats are intended to be used in connection with special spark plugs having corresponding bevel seats integral with the hard metal bodies thereof. Such special plugs can be initially installed at the factory without any diiculty as the equipment is there available for rigidly controlling the torsion applied to the spark plug to effect proper sealing engagement between the seats without damage to the bevel seat 12 by reason of the hard metal-to-hard metal contact between the bevel spark plug and cylinder head seats. However, when the initial spark plugs are replaced, the installation of the new spark plugs is frequently effected with an inadequate torsion, so that an improper seal is provided between the bevel seats, or with an excessive torsion, which results in damage to the bevel seats causing leakage between the seats and consequently poor engine performance. Such damage to the bevel seatl of the cylinder head can be remedied only by resurfacing of the seat. Further, the hard metal seat integral with the body of a special spark plug intended for use in a cylinder head having bevel seats may not seat properly upon the latter due to roughness of the surfaces of the cooperating seats resulting from corrosion or occurring during manufacture.

In accordance with the present invention, a gasket, preferably of a relatively soft metal having good heat conductivity, for example, copper or the like, is disposed between the bevel seat 12 of the cylinder head and the seat on the body of the spark plug to permit the tightening of the latter to the extent necessary to obtain a proper seal 4without the danger of damaging the seats by the contact of one hard metal with another hard metal.

In Figs. 1, 2 and 3, a gasket embodying the present invention is generally identified by the reference numeral 13 and is formed to permit the use of a conventional spark plug 14 having a radial seat 15 on the metal body 16 thereof in connection with a cylinder head having bevel seats 12, either at the time of the initial installation of the spark plugs, or as replacements for the original bevel seat spark plugs. The gasket 13 is in the form of a ring and has a flat upper surface 17 and a bevel 18 at the lower corner of its outer peripheral surface, the angle of the bevel 18 being substantially the same as the angle of the bevel seat 12. The inner diameter of the gasket 13 is large enough to permit the latter to be slipped over the threaded portion 19 of the spark plug body which screws into the threadedbore 11 of the cylinder head.

When the spark plug, 14 is tightened irrt-he bore 11,

the relatively soft metal gasket 13 is compressed between the seats 12 and 15 and deformed to the extent necessary to ensure good sealing contact with the seats, even when the surfaces of the seats are rough or pitted by corrosion or during the manufacture ofthe spark plug or cylinder head.

In the embodiment of the invention illustrated in. Figs. 4, 5 and 6, the cylinder head, spark plug and gasket, and the several parts thereof are identified by the samereference numerals Aemployed in connection with the corresponding parts in the embodiment of Figs. l, 2 and' 3, but with the letter a appended thereto. The gasket 13a, as in the case of the gasket 13, is intended to permit the installation of a conventional spark plug, 14a in a threaded bore 11a ofv a cylinder head 10a having a bevely seat 12a at the upper or outer end of the bore. The gasket 13a is also formed of a relatively soft, heat conductive metal and has a bevelled lower corner 18a on. the outer peripheral surface thereof for engagement with the bevel seat 12a. Further, the upper, radial surface f17a of the gasket 13a has an annular upwardly tapering ridge 20a projecting therefrom to engage, at its upper edge, against the radial seat 15a of. the spark plug body 16a. Since the area of contact of the ridge 20a with the seat 15a is relatively small, the axial force therebetween resulting from turning of the threaded portion 19a in lthe threaded bore 11a will cause a relatively great compressive stress to be applied to the ridge 20a for more easily conforming the shape of the edge of the latter to the surface of the seat 15a. The sloping surface contact between the bevel 18 or 18a and the bevel seat 12 or 12a provides a wedging effect as the spark plug is screwed into the bore of the cylinder head, thereby ensuring proper seating against the bevel seat.

It is apparent that the gaskets described above permit the use of any conventional spark plug having the correct standard thread and heat range for use with a particular engine having bevel seats in the cylinder head thereof, and eliminates the necessity of using special spark plugs with bevel seats. The gaskets embodying the invention also ensure against any seat damage resulting from the seating of two relatively hard metal surfaces against each other. Further, since the gaskets of relatively soft metal are deformable to conform to the seats of the spark plugs and cylinder head, the necessity for precision machining or grinding of the seats is eliminated without sacrificing the effectiveness of the sealing of the spark plugs in the cylinder head. The gaskets formed of a metal having good heat conductivity, such as, for example, copper or the like, provide maximum heat transfer between the spark plugs and the cylinder head to direct heat away from the electrodes of the spark plug to the exposed portion of the body and thereby increase the useful life of the spark plugs. Finally, gaskets embodying the present invention permit the repeated changing of spark plugs without damage to the seats of the cylinder head or spark plugs and provide proper seating, even when the seats are rough or scarred, to prevent leakage past the spark plugs and consequent poor engine performance. f

Although illustrative.` embodimentsoftheV invention have been described in detail herein with reference to the accompanying drawing, it is to be understood that the invention is not limited to those precise embodiments, and that various changes and modifications may be effected therein without departing from the scope or spirit of the invention except as defined in the appended claims.

What is claimed is:

l. In combination, a cylinder head having at least one `threaded spark plug receiving bore with a bevel seat at the outer end` of the latter, a spark plug. having a body with a threaded portion adapted: to. be. screwed: into said bore and a radial seat at the outer end of said threaded portion, and a relativelyv soft, ring-like gasketltting over said threaded portion and disposed betweensaid radial and bevel seats, said gasket having an. outer diameter smaller than the outer diameter of said radial seat, said gasket having a bevel at the outer peripheral edge thereof4 engaging said bevel seat and being applied axially against said' radial seat to provide an effective seat between said bevel and radial seats while protecting the latter from damage by seating contact between relatively hard surfaces.

2. In combination,4 a cylinder head having at least one bevel seat for the reception of a spark plug, a spark plug having a body with a radial seat, and a gasket of a relatively soft metal having good heat conductivity compressed between said radial and bevel seats, said gasket having an outer diameter smaller than the outer diameter of said radial seat, said gasket having a bevelat the outer edge thereof engaging said bevel Vseat and being applied axially against said radial seat to provide an effective seal between said radial and bevel seats while protecting the latter from damage by seating contact between hard surfaces and to provide eicient heat transfer between said cylinder head and said spark plug body for prolonging the useful life of the spark plug. p

3. In combination, a cylinder head having at least one bevel seat for the reception of a spark plug, a spark plug having a body with a radial seat, anda relatively soft gasket disposed between said radial and bevel seats, said gasket having an outer diameter smaller than the outer diameter of said radial seat, said gasket having a bevel at the outer edge thereof engaging said bevel seat and an annular ridge projecting from the side of said gasket facing toward said radial seat and engaging the latter over a relatively small area so that, as radial seat of the spark plug is moved toward said bevel seat of the cylinder head, a relatively great compressive stress is developed in said ridge to conform the latter to the configuration of said radial seat for providing an elective seal between said radial and bevel seats while avoiding damage to said seats by seating contact between hard surfaces.,

References Cited in the lle of this patent UNITED STATES PATENTS K Hart Oct. 3, 1939 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent NQ 2,921,109 12, 1960 Emil J. Novak It is hereby certified that error appears in theprinted specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 4., line 20, for "seat", second occurngnc,e read seal line 47, after "as" insert said Signed and sealed this 9th day of August '1960.a

(SEAL) Attest:

KARL H. AXLINE ROBERT C. WATSON Attestingr Officer Commissioner of Patents 

